The present invention relates to a front lid opening and closing assist with which a front lid of a keyboard instrument can be opened or closed more easily and safely.
As shown in FIG. 8, a keyboard instrument, namely a conventional grand piano 101, is provided with a lid 103 for the purpose of opening a top portion of a piano main body 102 such that acoustic effects can be increased at the time of performance as well as for the purpose of reflecting played sound at a predetermined angle.
The lid 103 comprises a front lid 103a and a back lid 103b. The front lid 103a is pivotably attached, via a hinge 103c, to a front edge of the back lid 103b, and when the lid 103 is in a closed position, the front lid 103a covers a folded-back music stand 104 for protection.
On the other hand, the back lid 103b is also pivotably attached, via hinges 105, to the top of a side wall of the piano main body 102 on the lower-key side, and has a plurality of receiving pans 108 and 109 disposed on its rear surface on the higher-key side. The receiving pans 108 and 109 receive and support a tip of either of a plurality of projecting sticks 106 and 107 of different lengths, both of which extend from the piano main body 102 on the higher-key side.
When opening the lid 103 to play the grand piano 101, a user first folds back the front lid 103a relative to the back lid 103b as shown in FIG. 8, and in this state lifts up the lid 103. The user then selects either of the projecting sticks 106 and 107, and inserts the tip of the selected stick 106 or 107 into its associated receiving pan 108 or 109, thereby supporting and setting the lid 103 in a desired open state.
Now, a problem is the weight of the front lid 103a, which is approximately 10 kg. This weight may not be much trouble for a strong man. However, it is sometimes difficult, especially, for women and children, to lift up the front lid 103a, and furthermore, it is very dangerous if they pinch their hands in the front lid 103a by accidentally dropping it.
The present invention was made to solve the aforementioned problem. More particularly, the object of the present invention is to provide a front lid opening and closing assist which enables a user to operate a front lid of a keyboard instrument more easily and more safely, at the time of adjusting an open state of the front lid.
In order to attain this object, there is provided a front lid opening and closing assist comprising a buffer to be interposed between a front lid and a back lid constituting a lid of a keyboard instrument, the front lid being pivotably connected to the back lid, for damping pivot motion of the front lid between a closed position where the front lid is level to the back lid, a neutral position where the front lid is perpendicular to the back lid, and an open position where the front lid is superimposed upon the back lid. The buffer comprises a first damping mechanism for damping the front lid when it is pivoted from the neutral position to the closed position, and a second damping mechanism for damping the front lid when it is pivoted from the neutral position to the open position.
According to this structure, in cases where the user opens (lifts up) the front lid relative to the back lid for opening of the entire lid, neither of the first and second damping mechanisms functions while the front lid is pivoted from the closed position to the neutral position. Accordingly, this operation of lifting up the front lid from the closed position is not hindered by those damping mechanisms. Now, in a usual status, once the front lid is pivoted beyond the neutral position, it spontaneously pivots toward the open position because of its own weight. However, this motion is damped by the second damping mechanism, which results in a slow pivot motion of the front lid. As a result, the user can safely superimpose the front lid upon the back lid, with only minimal force for supporting the front lid.
On the other hand, in cases where the user pivots the front lid to the closed position after closing the back lid, neither of the first and second damping mechanisms functions while the front lid is pivoted from the open position to the neutral position. Accordingly, this operation of lifting up the front lid from the open position is not hindered by those damping mechanisms. Now, in a usual status, once the front lid is pivoted beyond the neutral position, it spontaneously pivots toward the closed position because of its own weight. However, this motion is damped by the first damping mechanism, which results in a slow pivot motion of the front lid. As a result, the user can safely close the front lid, with only minimal force for supporting the front lid.
In this manner, when the front lid is laid down from the neutral position to either a closed or open position, the front lid is slowly pivoted because of a damping function of the corresponding damping mechanism. As a result, there is less risk of an accident that the user might catch his/her hand in the front lid by a sudden drop thereof, and further safety is ensured.
As a specific example of the first and second damping mechanisms, each damping mechanism may comprise a rotary damper for applying a rotational resistance within a predetermined range of rotation angles. A rotary damper, for example, a hydraulic-type rotary damper is useable, as described below.
The predetermined range of rotation angles may be set to be approximately 90 degrees from the neutral position to the closed position with respect to the first damping mechanism. Alternatively, it may be set from a position away from the neutral position at a predetermined angle (for example, from 10 to 30 degrees) toward the closed position, such that the first damping mechanism provides no damping force while the front lid is pivoted within the predetermined angle from the neutral position and start to provide a damping force when the front lid is pivoted beyond the predetermined angle toward the closed position. This is possible because the torque applied to the front lid by its own weight is small immediately after the front lid starts to pivot from the neutral position. In this manner, therefore, the pivot motion of the front lid is facilitated, rather than being damped, immediately after the start thereof from the neutral position. The setting of such a range of rotation angles where the damping force is applied to the front lid can be achieved by contriving the structure of the rotary damper, as described below. In the same manner, as to the second damping mechanism, the range of rotation angles may be set to be approximately 90 degrees from the neutral position to the open position, or it may be set such that a damping force is applied only after the front lid is pivoted beyond a predetermined angle from the neutral position toward the open position.
In addition, in view of installation errors, or the like, in fixing the first and second damping mechanisms to the front and back lids, it is also advantageous to set the predetermined range of rotation angles including a spare angle beyond the closed or open position. In this case, damping functions of the rotary dampers are still effective even after the front lid has reached the open or closed position. By this structure, the front lid itself can have some leeway in its pivot angles, and consequently, the front lid can be surely pivoted to a position where it is completely level relative to the back lid.
Also, the rotary damper may be provided with a spring member for applying an urging force which works in the same direction as a direction in which the rotational resistance of the rotary damper acts (that is, a direction in which the front lid is lifted up).
In this structure, if the rotary damper is a hydraulic type, a damping force caused by a spring force can be applied in addition to a damping force caused by a hydraulic pressure. Consequently, the rotary damper can be made relatively small. If the rotary damper is miniaturized, it is inconspicuous when fixed to the front and back lids, which is preferable in view of the appearance of the grand piano.
Also, in cases where the rotary damper is a hydraulic type and provided with the spring member, even when oil leaks are caused by age deterioration of the rotary damper or any other factor, a sudden drop of the front lid can be prevented by a function of the spring member, and safety is further ensured. Moreover, it is possible for the user to judge that the rotary damper has deteriorated when the velocity of pivot motion of the front lid increases. The user can then replace the rotary damper with a new one.
Furthermore, in this case, an urging force applied by the spring member works in a direction in which the front lid is lifted up. Consequently, when the front lid is pivoted from the closed position to the neutral position, or from the open position to the neutral position, the pivot motion of the front lid is facilitated by the urging force of the spring member. As a result, the front lid can be operated more easily, especially, by women and children.
As a specific constitution of the first and second damping mechanisms, each damping mechanism may comprise a first arm to be fixed to the front lid, a second arm to be fixed to the back lid, and a connection for connecting the first and second arms rotatably relative to each other. In this case, the rotary damper is disposed in the connection to damp the rotation of the first and second arms.
If the first and second damping mechanisms have the aforementioned constitution, it is preferable that the first damping mechanism is disposed in the vicinity of one end of the pivot shaft provided between the front and back lids, while the second damping mechanism is disposed in the vicinity of the other end of the pivot shaft between the front and back lids. By this arrangement, both the damping mechanisms are not obstacles to the inner structure of the piano main body. Further in this case, it is preferable for the first arm to have a thickness approximately equal to or smaller than the thickness of the front lid to be fixed into a notch formed on a side edge of the front lid, and for the second arm to have a thickness approximately equal to or smaller than the thickness of the back lid to be fixed into a notch formed on a side edge of the back lid. In this manner, the damping mechanisms can be a part of the front and back lids, thereby making the buffer itself inconspicuous. This is also desirable, especially, in view of appearance.